Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1997-10-30
2001-07-24
Jankus, Almis R. (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S076000, C345S078000, C345S079000
Reexamination Certificate
active
06266035
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to electroluminescent displays (“ELDs”) and more particularly to an ELD and ELD driver with improved brightness control.
ELDs comprise a matrix of pixels, each located at an intersection of a column and a row electrode. Electroluminescent material between the row and column electrodes illuminates when there is a voltage potential across the row and column electrodes. The voltage on the column electrodes is controlled by a column driver. The voltage on the row electrodes is controlled by a row driver. Typically, a voltage potential is applied sequentially to each of the row electrodes while a voltage is applied to the appropriate column electrodes to illuminate selected pixels in each row.
The brightness of each pixel in the ELD is related to the voltage across the pixel. Although the brightness can be controlled by varying voltage, there are several drawbacks. The brightness of the ELD is difficult to control with the voltage. For a given voltage, the rightness between two ELD panels may vary. The brightness of the ELD may also vary with temperature for a given voltage. Further, implementing more than a few voltage levels is expensive. Thus, even sixteen-level shades are expensive to implement using voltage control.
Some ELDs utilize variations in refresh rate to achieve brightness control. Generally, if a pixel is illuminated at a higher refresh rate, it will appear brighter to the human eye. If the pixel is illuminated less frequently, it will appear dimmer to the human eye. In order to implement brightness control, a single video frame may be displayed at a refresh rate several times higher than the video frame rate. For maximum brightness, a pixel would be illuminated during each of the several refresh cycles. By decreasing the number of times a pixel is illuminated over the number of refresh cycles, the apparent brightness of the pixel is controlled. However, this method is also expensive. In order to implement sixteen-level brightness, the refresh rate must be at least fifteen times the frame rate. 60 Hz is generally considered the minimum displayed frame rate to avoid flickering. Thus, the refresh rate to achieve sixteen-level brightness would have to be 900 Hz. Column and row drivers which have to refresh each of the pixels at 900 Hz are expensive. Increasing the number of shade levels further rapidly increases the cost even more.
SUMMARY OF THE INVENTION
The present invention provides a display system comprising an ELD controller which varies the voltage and refresh rate selectively in order to provide different brightness levels among the pixels in an ELD display. For each of the voltages which is available to be applied to the pixels, each of the available refresh rates is also available. As a result, the number of available brightnesses for each of the pixels is generally proportional the number of available voltages times the number of available refresh rates. The display system of the present invention is thus simpler and less expensive than those previously known.
REFERENCES:
patent: 4559535 (1985-12-01), Watkins et al.
patent: 4691144 (1987-09-01), King et al.
patent: 4839563 (1989-06-01), Boudreau et al.
patent: 4975691 (1990-12-01), Lee
patent: 4996523 (1991-02-01), Bell et al.
patent: 5075596 (1991-12-01), Young et al.
patent: 5459495 (1995-10-01), Scheffer et al.
patent: 5517207 (1996-05-01), Kawada et al.
patent: 5602559 (1997-02-01), Kimura
patent: 5781168 (1998-07-01), Osada et al.
patent: 5786797 (1998-07-01), Kapoor et al.
patent: 5898414 (1999-04-01), Awamoto et al.
patent: 5999150 (1999-12-01), Nighan et al.
patent: 6049324 (2000-04-01), Palalau et al.
patent: 0762374 (1997-03-01), None
patent: 0778556 (1997-06-01), None
patent: 2740598 (1997-04-01), None
patent: 2164776 (1986-03-01), None
Mano et al., “TFT-LCD Drive Method and Driver LSI”, 1996, pp. 177-182.
Jankus Almis R.
Lear Automotive Dearborn Inc.
Niro Scavone Haller & Niro
Tran Henry N.
LandOfFree
ELD driver with improved brightness control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with ELD driver with improved brightness control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ELD driver with improved brightness control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2511494